The role of life history in the relationship between population dynamics and environmental variability in two Mediterranean stream fishes

Abstract

Chub Squalius torgalensis and nase Chondrostoma lusitanicum, in a Mediterranean stream, showed important differences in life‐history traits and population dynamics. Both species reached mean maturity at age 2 years. Chub lived up to age 5 years, spawned in March to June, grew at a maximum rate of 0·59 mm mm−1 year−1 and showed a low reproductive allocation, with fecundity and egg size increasing with body size. Nase lived up to age 4 years, spawned in January to April, grew at a maximum rate of 0·46 mm mm−1 year−1 and showed a high reproductive allocation, with egg size independent of body size. Both chub and nase showed moderate fluctuations in population size during 1991–1998, but differed in factors driving density at age. Density of age 1 year juvenile chub decreased following severe summer droughts and proportionate survival prevailed thereafter. Density of age 2 year adult nase decreased following severe spring floods, but neither environmental nor parental stock effects were detected for juveniles and older fishes. The results illustrated the interplay between life history and environmental variability in driving fish population dynamics, with impacts of both summer droughts and spring floods being contingent on species‐specific patterns of spawning and reproductive investment.

Comparisons of the genetic structure of Squalius populations (Teleostei, Cyprinidae) from rivers with contrasting histories, drainage areas and climatic conditions based on two molecular markers

“…Considering the divergence rate of the cytb gene estimated by Dowling et al (2002), a mutation rate of 12.704  10 À6 (0.0053  10 À6 substitutions/lineage/year  799 sites  time of generation of 3 years) was used. The generation time was calculated as the average age of maturation retrieved from several studies on the biology of S. pyrenaicus (Fernández-Delgado and Herrera, 1994;Geraldes and Collares-Pereira, 1995), S. torgalensis (Magalhães et al, 2003) and S. carolitertii (Maia et al, 2006).…”

Influences of environmental and chemical parameters on the spatial growth patterns of four riverine cyprinid fishes

“…Nevertheless, anthropogenic activities that modify physical habitats and water quality can also strongly influence growth rates due to the shifts in geomorphic, hydrologic and chemical characteristics of rivers that result in significant changes in the structure and function of fish communities (Welcomme et al, 2006;Beardsley and Britton, 2012;Britton et al, 2013). Moreover, considerable interspecific differences are often evident (Magalhães et al, 2003;Šimková et al, 2006) with, for example, species such as roach Rutilus rutilus tending to grow faster and dominate lowland river fish communities receiving high nutrient loads (Willemsen, 1980;Beardsley and Britton, 2012), with species such as European barbel Barbus barbus increasing their growth rates and importance in communities as loadings decrease . Nevertheless, there remains considerable spatial uncertainty over the respective responses of species within cyprinid fish communities to these anthropogenic disturbances (Britton, 2007).…”

Reproductive ecology of Odontostilbe pequira (Steindachner, 1882) (Characidae, Cheirodontinae) in the Paraguay River, southern Pantanal, Brazil

“…The reproduction of species with different patterns of life history is affected by local environmental conditions (Humphries et al 1999;Magalhães et al 2003;Zeug and Winemiller 2007), causing them to show in their reproductive strategy, a set of variable tactics which are adapted in response to the quality and variability of abiotic conditions, food availability and predation (Vazzoler 1996;Wootton 1998). Thus, the study of reproductive tactics, such as length at first maturity, sex ratio, reproductive period, type of spawning and fecundity (Vazzoler 1996;Hutchings 2002), are essential for the understanding of how these characteristics are adapted for maximizing reproductive success in a particular environment (Matthews 1998).…”